Initial commit

README.md

@@ -0,0 +1,22 @@
+# struct
+
+A simple unix utility for structuring string data on the command line.
+
+# example usage
+
+## string output
+```
+$ ls -l | struct -fields permissions,count,user,group,,,,,file_name -output string
+permissions:-rw-r--r-- count:1 user:adriano group:staff 84 Sep 23 22:55 file_name:README.md
+permissions:-rw------- count:1 user:adriano group:staff 39 Sep 23 21:08 file_name:go.mod
+permissions:-rw-r--r-- count:1 user:adriano group:staff 2531 Sep 23 22:54 file_name:struct.go
+```
+
+## json output
+
+```bash
+$ ls -l | struct -fields permissions,count,user,group,,,,,file_name -output json
+{"count":"1","file_name":"README.md","group":"staff","permissions":"-rw-r--r--","user":"adriano"}
+{"count":"1","file_name":"go.mod","group":"staff","permissions":"-rw-------","user":"adriano"}
+{"count":"1","file_name":"struct.go","group":"staff","permissions":"-rw-r--r--","user":"adriano"}
+```

go.mod

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+module adriano.fyi/pkg/struct
+
+go 1.12

struct.go

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+package main
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type fields []string
+
+var fieldsFlag fields
+var sepFlag string
+var outFlag string
+
+var in string
+var fieldsProvided int
+
+func (f *fields) String() string {
+	return fmt.Sprint(*f)
+}
+
+func (f *fields) Set(value string) error {
+	if len(*f) > 0 {
+		return errors.New("fields switch already set")
+	}
+
+	for _, field := range strings.Split(value, ",") {
+		*f = append(*f, field)
+	}
+
+	return nil
+}
+
+const (
+	defaultFieldSeparator = " "
+	defaultOutput         = "string"
+	fieldsUsage           = "comma-separated list of fields corresponding to the input data's fields\n\n" +
+		"Example\n\n" +
+		"$ echo \"foo1 bar1\" | struct -fields foo,bar\n" +
+		"$ foo:foo1 bar:bar1\n"
+	outputUsage    = "the desired output format: json or string"
+	separatorUsage = "the character that separates fields in the input data"
+)
+
+func init() {
+
+	flag.Var(&fieldsFlag, "fields", fieldsUsage)
+	flag.StringVar(&sepFlag, "separator", defaultFieldSeparator, separatorUsage)
+	flag.StringVar(&outFlag, "output", defaultOutput, outputUsage)
+	setupFlags(flag.CommandLine)
+
+	flag.Parse()
+}
+
+func setupFlags(f *flag.FlagSet) {
+	f.Usage = func() {
+		fmt.Println("\nCreate structured data input strings")
+
+		f.PrintDefaults()
+	}
+}
+
+var sb strings.Builder
+var jsonMap = make(map[string]string)
+
+func main() {
+	fieldsProvided = len(fieldsFlag)
+
+	scanner := bufio.NewScanner(os.Stdin)
+
+	var i int
+	var field, v string
+
+	for scanner.Scan() {
+		in = scanner.Text()
+
+		inputFields := strings.Fields(in)
+
+		for i, v = range inputFields {
+			if i < fieldsProvided {
+
+				field = fieldsFlag[i]
+			} else {
+				field = ""
+			}
+
+			buildOutput(field, v)
+		}
+
+		fmt.Println(out())
+	}
+}
+
+func out() (out string) {
+	if outFlag == "string" {
+		out = sb.String()
+		sb.Reset()
+	} else if outFlag == "json" {
+		o, _ := json.Marshal(jsonMap)
+		out = string(o)
+		for k := range jsonMap {
+			delete(jsonMap, k)
+		}
+	} else {
+		out = ""
+	}
+
+	return
+}
+
+func buildOutput(field, value string) error {
+	if outFlag == "string" {
+		buildString(field, value)
+	} else if outFlag == "json" {
+		buildJSON(field, value)
+	} else {
+		return errors.New("invalid output option")
+	}
+
+	return nil
+}
+
+func buildString(field, value string) {
+	if field != "" {
+		sb.WriteString(field)
+		sb.WriteString(":")
+		sb.WriteString(value)
+		sb.WriteString(sepFlag)
+	} else {
+		sb.WriteString(value)
+		sb.WriteString(sepFlag)
+	}
+}
+
+func buildJSON(field, value string) {
+	if field == "" {
+		return
+	}
+
+	jsonMap[field] = value
+}